For years the only company that made 7.7 brass was Norma and it was very soft, leaving you with a low number of reloads. You can make 7.7 brass from 06 brass and simply fireform it with a stout load, expanding the web. The bullet supply are 303 British bullets. A 30 cal mould that throws bullets slightly oversized will work with a .311 sizer, if your groove diameter is .311, the Arisaki, all of them, has less than standard bores. To shoot cast you will need to slug your barrel. The dies are a different matter, I do not know of anyone that makes dies today except as a special order.
My dies are not here at the house, they are at the farm, but I believe they are Redding or Pacific. Great thing about having half your junk moved and half at the house before moving it. You are welcome to borrow the dies to make yourself some brass and reload yourself some shootable ammo if you can not find the dies. Of course you need to return them.
Ed
Thank you for offering me a die set on loan. I will purchase the set Bo sent me a link to if no offers come in this week. The type 99 rifle I have looks like a pipe screwed into a receiver. I was thinking wall hanger, but a friend sent me five pieces of reformed brass from 30-06 and 5 .311 150's. My son and I shot it the other day. I was very surprised how well it shot. Here is a pic of our target.This was at 50 yards on the right was my son shooting off bench and left was me shooting off hand. I thought I would reload and shoot some more.
There was an older set for sale at the gun show this weekend...by the table in the back with all the WW2 German stuff...not too sure if that helps. Don't know that vendor, maybe someone on here does...
As long as the rifles were made from mid war to before the war they are usually well made, plus the type 99 has a chrome bore, was built for jungle warfare, so the outside can be pretty rough but the rifle might well have a very good inside and be a good shooter.
Ed